Multiply paper sacks



June 19, 1956 W. v. OWENS 2,751,141

MULTIPLY PAPER SACKS Filed July 7, 1952 Z4 f4 Mza/ 7a 24 l MULTIPLY PAPER SACKS William Vincent Owens, Northtleet, England, assignor to Paper Sacks Limited, Bristol, England Application July 7, 1952, Serial No. 297,491

Claims priority, appiication Great Britain July 12, 1951 3 Claims. (Cl. 229-55) This invention relates to multiply paper sacks of the kind in which longitudinal slits are formed which extend inwardly from the ends of the sack such that on closing the ends of the sack the end triangular formations terminate in an inward portion having parallel edges extending transversely across the sack while the side folding formations have parallel edges extending longitudinally of the sack. When the various plies of the sack are assembled these slits are coincident and it has been found there is a danger of the plies tearing at this point, and

there is also a risk of seepage of the contents of the sack. f

It is an object of the invention to provide an improved construction of sack of the kind described whereby the above disadvantages are eliminated.

The invention consists in a multiply paper block bottom bag wherein the bag tube plies are transversely perforated at bag length and are longitudinally slit to provide corner forming parts such that when the plies are assembled the slits are transversely staggered to provide said corner forming parts of increasing width from the outer to the inner ply, the length of such parts being equal in all plies.

According to the invention in a multiply paper sack of the kind described the slitting of the various plies is located at different distances from the longitudinal axes of the webs whereby when the webs are assembled the slits are relatively staggered and corner forming parts of varying width are formed which provide exposed portions of each ply for adhesive sealing.

The relative lateral displacement of the slits may vary as desired.

The invention may be applied to a multiply sack having staggered end margins and in such the relative displacement of the slits will provided a sealing area of each ply at the ends of the side closing flap.

In the accompanying drawings,

Figure l illustrates a layout of one end of the ply sheets of a bag constructed according to the invention;

Figure 2 illustrates the plies of Figure l separated from one another;

Figures 3, 4 and 5 illustrate the steps in folding an end closure.

In carrying the invention into effect according to one convenient mode by way of example, as applied to the manufacture of a 3-ply sack, a series of webs l, 2, 3, are fed from supply reels to an assembly position to provide a composite web. Each web is transversely perforated for saclf; length. Thus, at the corresponding ends of a set of bag lengths, the intermediate ply 2 will be perforated on a rectilinear line 2a, while the inner ply 1 and the outer ply 3 will have shouldered and notched perforations la and 3Q respectively. Each ply is longitudinally slit on bota sides of the perforation to form the parallel edges of the folding in end triangular formation. The slitting of the outer ply 3 is shown at 21; that of the intermediate ply 2 is shown at 23 while that of the inner ply 1 is shown at 24. This slitting is effected equidistantly from the edge folding lines 22 of the sack length. It will be States Patent titl noted that the slits are shown open for clarity and that there is no removal of material. The position of the slits 21, 23, 24 in the various webs 3, 2, 1 is appropriately displaced transversely so that the distance between such parallel edges of the triangular folds on the plies will increase from the outermost ply to the innermost ply, as seen in Figure 3. In other words when the corner formation of the sack length 28 is folded the intermediate ply 2 and inner ply l will have exposed areas 29, 30 at such parallel edges. Correspondingly there will be exposed areas 33 at the ends of the outer ply on the side ap 31 and exposed areas 34, 35 on the outer and intermediate plies 3 and 2 at the ends of the side ap 32.

The disposition and shape of the perforations 1a, 2a, 3a is such that when the webs 1, 2 and 3 are assembled and the sack length severed by tension thereon the end margins on the sack length will be staggered as indicated in Figure l and the transverse edges of the portions 25, 26, 27 will coincide.

rhe relative disposition of the longitudinal slits 21, 23, 24 in the webs may vary with corresponding marginal ex` posure of the plies when folding to form the bottom closure.

The longitudinal extent of the longitudinal slits 2l, 23, 24 is preferably such that when the end is folded the inner ends of the slits coincide with the folded edges 28a of the end triangular formation 28, such edges being indicated by the lines Ziib in Figure l,

With the relative transverse disposition of the slits- 21, 23, 24 the risk of tearing of the plies is eliminated with consequent avoidance or lessening of seepage.

Moreover, in the closing of the end of the sack additional surface area of the various plies will be exposed and be available for adhesively securing the side folding portions to one another at their ends and also to the end fold portions.

In the first fold in forming the block bottom closure as illustrated in Figure 3 the triangular corner of formations 23 will include the transverse exposed areas 29, 36 which will be available for adhesive sealing.

In the next fold illustrated in Figure 4 the exposed areas 34, 35 of side Hap 32 will be adhesively secured to the outer ply of the corner formation 28, the exposed parts 29, 3i) of such flap also being adhesively secured to the same ply.

In the final fold illustrated in Figure 5 the exposed areas 29, 39 and the staggered margin areas 36, 37 and 3S will be adhesively secured to the corner formation 28 and the parts 39, 4i), 41 of the folded over `side Hap. In this final fold the outer ply of side ap 31 will provide an integral label 42 having exposed sealing areas on all sides.

At the corner of the bag to form the valve the pasting will be such as only to avoid sealing to the corner flap, and an inwardly extending valve sleeve may be provided at such corner.

I claim:

l. A multiply paper bag having an end block bottom closure comprising a pair of side flaps of rectangular shape and a pair of end flaps of combined triangular and rectangular shape, the plies of the side aps being stepped longitudinally of the bag so that the plies of a irst one of said side flaps are progressively longer from the inner to the outer ply, while the plies of the second one of said side flaps are progressively longer from the outer to the inner ply, the lateral edges of both the side flaps being stepped to expose areas of all plies for adhesive sealing, the inner terminal edges of the plies of both of the end aps being coincident, the lateral edges of the plies of the rectangular portions of the end aps being stepped to expose areas of all plies for adhesive sealing, said second side ap being turned over a line transverse to said bag length and adhered to parts of said end flaps, and said first sider flap being turned over a line transverse to said bag length and having its stepped plies overlying and adhered to parts of said end flaps and the stepped plies of said second side tlap.

2, A multiply paper bag in accordance with claim l, in which the plies forming said bag are slitted longitudinally at respectively different distances from the longitudinal center line of the bag to provide the stepped relationship of the lateral edges of the side and end aps.

3. A multiply paper bag in accordance with claim 2, in which the bag is formed of three plies, .-v'ith the outer and inner plies having portions terminating on transverse lines spaced longitudinally from the termination of the References Cited in the tile of this patent UNlTED STATES PATENTS 1,821,207 Cornell Sept. 1, 1931 2,176,499 Hoppe et al Oct. 17, 1939 10 2,460,885 Hoppe Feb. 8, 1949 FORElGN PATENTS 508,603 Great Britain July 4, 1939 

